This invention relates to a fluid impelling device and to electronic apparatus.
It is well known to induce a flow of a fluid such as a liquid or gas by employing a mechanical device which impels such flow. For fluids which are liquid, such devices are commonly known as pumps. For fluids which are gases, such as air, such devices are variously known as fans or compressors, depending in part on the degree to which the pressure of the gas is raised by operation of the device. Particularly as to devices which fall into the category of fans, two particular forms are in wide use: the radial blade fan and the scroll or squirrel cage fan.
Radial blade fans are widely used to move air in homes, sometimes as overhead fans. As employed in smaller sizes to provide a flow of cooling air for devices such as electronic apparatus, such fans usually have a support for the rotating blade element which in is the form of a spider frame. Such spider frames are disposed in the airflow generated by the rotating radial blades and, when the fan operates at a significant rotational speed, cause a “siren” effect due to the passage of the blades past the spider frame. The noise so generated has become problematical in electronic devices or systems intended for use in quiet locations such as a home or office. That noise has been a problem with computer systems.
Scroll or squirrel cage fans may be designed to operate somewhat more quietly. However, such fans deliver lower air flows from a greater volume of occupied space, and thus are a poor design choice for confined areas such as the housings of electronic systems. Thus the class of fans has been little used and is generally deemed unacceptable in such applications.
With the foregoing in mind, there is a need for an alternative device for impelling fluid flow, and in particular for the application of such a device to providing a cooling air flow for electronic systems such as computer systems of the desktop or notebook types.